1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device technology field, and more particularly to a source driving module of an LCD panel and an LCD panel comprises the source driving module in an LCD device.
2. Description of Related Art
The liquid crystal display (LCD) device is a flat and ultra-thin display device. It consists of a number of color or monochrome pixels, placed in front of the light source or reflect surface. The power consumption of the LCD device is very low, and it has a high-quality, small size, light weight, so that people are favored to become the mainstream display device. The current LCD device is mainly based on the thin film transistor (TFT). The LCD panel is the main component of the LCD device. The liquid crystal panel generally includes a color filter substrate and a TFT array substrate disposed oppositely and a liquid crystal layer sandwiched between the two substrates.
The driving of the LCD panel is by the gate electrode driving module and the source electrode driving module to respectively provide a scan signal and a data signal to the LCD unit. The voltage difference between different voltage of the data signal and a common electrode voltage cause the liquid crystal molecular to rotate a different angle in order to form the brightness difference. That is, the LCD panel displays with different grayscales. In the LCD panel, the relation curve between the data signal voltages and grayscales is called a Gamma curve. Using 8bit LCD panel as an example, it can display 28=256 grayscales, and they are corresponding to 256 different Gamma voltages. The Gamma voltages divide the change process from white color to black color into 2N equal parts.
In order to improve the display quality of the LCD panel, the Gamma correction has been widely used. In practical application, it usually selects the crucial turning points in the Gamma curve, and through adjusting the voltages of turning points to achieve adjustment of the Gamma curve. Using LCD panel with 256 grayscales as an example, in order to protect the LCD unit better, for the same display unit, it usually utilizes mutual driving method of a positive polarity voltage and a negative polarity voltage. In the Gamma curve as shown in FIG. 1, VD1˜VD20 have 20 turning points (00H, 01H, 02H, 1FH, 3FH, 7FH, BFH, DFH, FEH and FFH, that is the 0, 1st, 2nd, 31rd, 63rd, 127rd, 191rd, 223rd, 254rd and 255rd grayscales) to be selected for adjusting, which is that we usually refer to 20 regulated voltages with binding. The source driving IC further generates 256 Gamma voltages according to the 20 regulated voltages to realize the display of 256 grayscales as the schematic diagram shown in FIG. 2.
In the prior art, there are two methods to generate VD1˜VD20: one method is using a resistor string to divide a voltage to obtain 20 regulated voltages, and then utilizing buffer amplifier chip to amplify the driving capacity. However, the Gamma voltages generated by this method are difficult to adjust; the other method is using P-Gamma (programmable gamma correction) to implement programmable regulated voltages. The Gamma voltages generated by this method is easy to be adjusted, but using P-Gamma IC to generate 20 regulated voltages, the number of the output channels is more, and the cost is higher.